Luminaire

ABSTRACT

Luminaire for indoor industrial use has an optical assembly having a diameter substantially greater than its height and adapted to be mounted at a relatively low height above the floor. The optical assembly comprises a reflector with fluted concave upper portion and an outwardly flaring lower skirt portion to which a large diameter dish-shaped refractor is secured. The refractor has an annular side wall formed with horizontal rows of prisms which depress part of the incident light and reflect the remaining light rays upwardly toward the ceiling. The bottom panel of the refractor is formed with radial light dispersing flutes.

United States Patent Willis, Jr. et al.

[54] LUMINAIRE [72] Inventors: Candler A. Willis, Jr., Zirconia,

N.C.; John R. Judge, Mobile, Ala.

[73] Assignee: General Electric Company [22] Filed: March 12, 1971 21Appl. No.: 123,553

521 u.s.ci. ..240/93, 240/106 R, 240/1061, 240/149 [51] Int.Cl...F2lv13/04 [58] Field of Search.....240/25, 92, 93, 103 R, 103 B,

[56] References Cited UNITED STATES PATENTS D222,103 9/1971 Anderson..D48/23 481,288 8/1892 Stanley .240/93 3,329,812 7/1967 Harling..240/93 3,443,260 6/1969 Wince et al..... 240/106 R 8/191 1 Losey..240/92 [151 3,705,303 [4 1 Dec. 5,1972

OTHER PUBLICATIONS Uddeholm- Lighting Masts Specification, 1965, page 22sct o 29.0

Primary Examiner-Samuel S Matthews Assistant Examiner-Russell E. Adams,Jr. Attorney-Sidney Greenberg, J. Wesley l-laubner, Frank L. Neuhauser,Oscar B. Waddell and Joseph B. Forman 5? ABSTRACT Luminaire for indoorindustrial use has an optical assembly having a diameter substantiallygreater than its height and adapted to be mounted at a relatively lowheight above the floor. The optical assembly comprises a reflector withfluted concave upper portion and an outwardly flaring lower skirtportion to which a large diameter dish-shaped refractor is secured. Therefractor has an annular side wall formed with horizontal rows of prismswhich depress part of the incident light and reflect the remaining lightrays upwardly toward the ceiling. The bottom panel of the refractor isformed with radial light dispersing flutes.

8 Claims, 8 Drawing Figures I LUMINAIRE The present invention relates tolighting fixtures, and particularly to luminaires of industrial indoortype.

It an object of the invention to provide a luminaire of the above typewhich spreads light over a large floor area when mounted at a relativelylow height.

Another object of the invention is to provide a luminaire of the abovetype wherein the luminaire brightness or glare is minimized, especiallyin the zone between vertical angles of between about 45 to 90. Byvertical angles is meant the angle up from nadir defined by a light rayrelative to the vertical axis of the light source.

Still another object of the invention is to provide a luminaire of theabove type from which a portion-of the light is directed toward theceiling to minimize contrast. I i

A further object of the invention is to provide a luminaire of the abovetype which has a relatively low overall profile;

Other objects and advantages will become apparent from the followingdescription and the appended claims.

With the above objects in view, the present invention in one of itsaspects'relates to a luminaire comprising,

in combination, an optical assembly comprising a reflector having anupper portion and a lower downwardly flaring skirt portion defining anopen bottom, and a generallydish-shaped refractor having an open top anda closed bottom, the reflector and refractor being connected to eachother at their peripheries with the refractor arranged below andenclosing the bottom of the reflector, the optical assembly beingsubstantially greater in overall diameter than in height, and a lampmounted in'the optical assembly, the refractor having a peripheral sidewall formed with prisms for depressing light rays from the lampdownwardly toward the area to be illuminated by the luminaire.

The invention will be better understood from the following descriptiontaken in conjunction with the accompanying drawings in which:

FIG. 1 is a view in elevation, partly broken away, of an industrialluminaire embodying the invention;

FIG. 2 is a top plan view of the refractor employed in the opticalassembly of the FIG. 1 luminaire;

FIG. 3 is a bottom plan view of the main luminaire reflector of theoptical assembly;

FIG. 4 shows a segment of the luminaire reflector as viewed along theline 4-4 in FIG. 1;

FIG. 5 is a somewhat schematic view of a vertical section of a portionof the luminaire optical assembly showing the path of light raystherein;

FIG. 6 is a view in vertical section of a portion of the refractor takenalong the lines 6-6 in FIG. 2;

FIG. 7 is an enlarged detail view of the side wall' prisms of therefractor; and

FIG. 8 is an enlarged cross-sectional view of a portion of the bottompanel of the refractor taken along the lines 8-8 ofFIG. 6.

Referring now to the drawings, and particularly to I FIG. 1, there isshown an industrial luminaire compris- Ballast housing 1 is formed withcooling fins In for radiating and dissipating heat generated therein bythe electrical operating components. Suspended from ballast housing lbelow the open bottom thereof is optical assembly 5 comprising reflector6 and refractor 7.

Reflector 6 is formed of a somewhat conical upperv portion 6a open atits top and a lower outwardly flaring skirt portion 6b, with bothreflector portions having reflecting flutes formed in the walls thereof,as seen in FIG. 3 wherein such flutes are shown only in one sector forthe sake of simplicity. Refractor 7 is a shallow, somewhat dish-shapedtransparent member having light control prisms extending around theouter surface of its peripheral wall. In the optical assembly, as seenin FIG. 1, the lower rim of reflector skirt portion 6b mates with theupper flanged rim of refractor 7, and

' they are securely joined together in permanent sealed relation bysuitable means, such as by forming the reflector rim into'an annularchannel 6c in which the annular flanged rim of refractor 7 is receivedand held.

Lamp 8 is arranged in optical assembly 5 with its base down and mountedin that position by bracket 1.0. Bracket 10 is generally V-shaped andsecured at its upper arms to opposite upper portions of reflector 6. Theapex of bracket 10 at its bottom is formed with a seat 10a in which lampsocket 9 with support bracket 9a is received and suitably secured. Insuch arrangement, lamp socket 9 is located closely adjacent the innersurface of the bottom panel of refractor 7, and lamp 8 extends upwardlyin the optical assembly. The light center LC of lamp 8 is thus arrangedin the proper position as shown in FIG. 1 relative to reflector 6 andrefractor 7 to provide the desired light distribution.

Optical assembly 5 is detachably connected to ballast housing 1 by meansof binge l1 and latch 14 soas to permit the optical assemblyto be swungdown from ballast housing 1, thus providing access to the interior ofthe optical assembly. A separable electrical connection between thedetachable parts is provided by electrical plug 16 secured to reflector6 and electrical receptacle 17 secured to ballast housing 1 as shown inFIG. l.-These and other mechanical features are more fully disclosed inco-pending application of Judge at al, Ser. No. 123,685, filed Mar. 12,I971, and assigned to the same assignee as the present invention. 7

In a typical luminaire constructed in accordance with the invention, theoverall diameter of optical assembly 5 at the junction of reflector 6and refractor 7 is about 31 inches, the overall height of the unitincluding ballast housing 1 and optical assembly 5 is about 21 inches,and the height of the optical assembly 5 is about 12 inches with theheight of refractor 7 being only about 4 inches. Thus, the overalldiameter of the optical assembly is substantially greater than theoverall height of the entire unit and more than twice the height of theoptical assembly. Because of the relatively large size of the refractorused in such a luminaire, it would usually be made of a syntheticplastic material such as an acrylic resin. Such a material is subject todiscoloration if exposed to excessive heat due to close proximity to thelamp. By arranging lamp 8 with its base down, adequate spacing isprovided between refractor 6 and the relatively hotter bulb portion oflamp 8 while still utilizing the space adjacent refractor 6 for thecooler lamp base and socket member 9. A further advantage in thisarrangement is that the height of the ballast housing can be reducedsince it need not accommodate the lamp socket, which in a base-uparrangement would have to be placed within the ballast housing so thatthe light center of lamp 8 can be correctly located at the properoptical position relative to the reflector flutes 6d and the refractorprisms 7a, as more fully disclosed herein. Such proper positioning ofthe light center of lamp 8 is necessary to provide the desireddistribution of light on the floor to be lighted as well as to avoidundue glare from the luminaire. In addition, the relatively low profileof the luminaire thus achieved makes it feasible to use the luminaire inareas having relatively low ceilings.

As seen in the embodiment illustrated in FIG. 1, lamp 8 is arranged sothat its light center LC is arranged somewhat above the bottom of upperreflector portion 6a. The latter reflector portion is relatively steeperin slope than reflector skirt portion 6b, and whereas the interiorsurface of reflector portion 6a is generally concave, reflector skirtportion 6b is straight in vertical section. As a result, as seen in FIG.5, light rays from the light center LC of lamp 8 which are incident onupper portion 6a are reflected downwardly therefrom toward the oppositeside of the luminaire, while light rays striking skirt portion 6b arereflected downwardly and outwardly therefrom toward the same side of theluminaire.

As seen in the generally horizontal section of reflector portion 6ashown in FIG. 4, flutes 6d have transversely convex inner reflectingsurfaces so as to spread incident light rays in horizontal (i.e.,lateral) directions. Similar flutes formed in skirt portion 6b similarlyhorizontally spread the light rays incident thereon.

Arranged at the open bottom of ballast housing 1 above the top openingof main reflector 6 (see FIG. 1) is accessory reflector 19 secured atits central portion to housing 1 by suitable means. As shown in FIG. 5,reflector 19 has a downwardly dished central portion 19a, a flat annularintermediate portion 19b extending substantially horizontally, and adownwardly sloping outer rim portion 19c. The light rays from lamp 8striking central portion 190 are deflected therefrom downwardly andoutwardly away from the lamp axis, intermediate portion 19b reflectslight rays downwardly at smaller vertical angles than those reflectedfrom portion 190, and reflector rim portion 190 reflects light rays backtoward the opposite side of the luminaire. Reflector rim portion 19c ispreferably formed with flutes on its reflecting surface similar to thoseof main reflector 6 as shown in FIG. 4 to horizontally spread theincident light rays. In general, the light rays reflected from accessoryreflector 19 as well as those reflected from main reflector portion 6aare directed downwardly through the bottom panel 7b of refractor 7. Asseen in the plan view of FIG. 2, bottom panel 7b is formed on its innersurface with radially extending flutes 7e or the like, which serve (seeFIG. 8) to disperse the light rays emanating therefrom so as to spreadthem over the area to be illuminated below the luminaire. Flutes 7e aretransversely convex but are of substantially constant refractive poweralong their lengths, so that the emanating light rays are fanned out invarying vertical angles in circumferential direction without anappreciable change in vertical angle in radial directions as between aparticular incident light ray and a corresponding emanating light ray.

As seen in FIG. 5, the light rays from lamp 8 which are reflected fromreflector skirt portion 6b are incident on the prismatic side wall 7a ofrefractor 7, and a portion of direct light rays from lamp 8 are alsoincident thereon. Side wall 7a is formed on its outer surface withannular parallel rows of horizontal prisms, the rows from top to bottombeing of decreasing diameter so as to be offset inwardly from oneanother as shown. Each prism (see FIG. 7) has a substantially horizontalreflecting surface 7c and a substantially vertical refracting surface7d. By virtue of this structure and the arrangements described above,light rays incident on refractor wall 7a are in part refracted anddepressed by vertical wall 7d of the prisms and in part are reflected byhorizontal face of the prisms so as to be directed upwardly andoutwardly from the luminaire. As a result of this double-acting functionof prisms 7a, a portion of the light is directed toward the ceiling tominimize con trast between the illumination of the floor and thecelling, light rays are spread over a wide floor area even when theluminaire is mounted at a relatively low height, and the brightness(glare) from the luminaire in the zone of about 45 to vertical angles isconsiderably reduced. Excessive brightness is also minimized due to therelatively large area of light emission from the large size refractor.

While the present invention has been described with reference toparticular embodiments thereof, it will be understood that numerousmodifications may be made by those skilled in the art without actuallydeparting from the scope of the invention. Therefore, the appendedclaims are intended to cover all such equivalent variations as comewithin the true spirit and scope of the invention.

What we claim as new and desired to secure by Letters Patent of theUnited States is:

1. A luminaire comprising, in combination, an optical assemblycomprising a reflector having an upper portion and a lower downwardlyflaring skirt portion defining an open bottom, and a generallydish-shaped refractor having an open top and a closed bottom, saidreflector and said refractor being connected to each other at theirperipheries with said refractor arranged below and closing the bottom ofsaid reflector, said optical assembly being substantially greater inoverall diameter than in height, and a lamp mounted in said opticalassembly and having a light center arranged above the bottom of saidreflector, said refractor having a peripheral side wall formed on itsouter surface with annular rows of prisms having substantially verticalrefracting surfaces and substantially horizontal reflecting surfaces,said substantially vertical refracting surfaces depressing light raysincident thereon from said lamp downwardly from said optical assembly,and said substantially horizontal reflecting surfaces redirecting lightrays incident thereon from said lamp upwardly from said opticalassembly.

2. A luminaire as defined in claim 1, said refractor having a bottompanel formed with a plurality of elongated refracting portions radiatingfrom the center of said bottom panel for circumferentially spreadinglight rays emanating from said panel.

3. A luminaire as defined in claim 2, said elongated radiatingrefracting portions comprising transversely convex flutes formed on theinner surface of said refractor panel.

4. A luminaire as defined in claim 3, said flutes being 5 ofsubstantially constant refractive power along their lengths.

5. A luminaire as defined in claim 1, a ballast housing arranged aboveand connected to said optical assembly for supporting the same, and anaccessory reflector mounted at the bottom of said ballast housing abovesaid upper reflector portion for reflecting light rays 1 nuvm run-l

1. A luminaire comprising, in combination, an optical assemblycomprising a reflector having an upper portion and a lower downwardlyflaring skirt portion defining an open bottom, and a generallydish-shaped refractor having an open top and a closed bottom, saidreflector and said refractor being connected to each other at theirperipheries with said refractor arranged below and closing the bottom ofsaid reflector, said optical assembly being substantially greater inoverall diameter than in height, and a lamp mounted in said opticalassembly and having a light center arranged above the bottom of saidreflector, said refractor having a peripheral side wall formed on itsouter surface with annular rows of prisms having substantially verticalrefracting surfaces and substantially horizontal reflecting surfaces,said substantially vertical refracting surfaces depressing light raysincident thereon from said lamp downwardly from said optical assembly,and said substantially horizontal reflecting surfaces re-directing lightrays incident thereon from said lamp upwardly from said opticalassembly.
 2. A luminaire as defined in claim 1, said refractor having abottom panel formed with a plurality of elongated refracting portionsradiating from the center of said bottom panel for circumferentiallyspreading light rays emanating from said panel.
 3. A luminaire asdefined in claim 2, said elongated radiating refracting portionscomprising transversely convex flutes formed on the inner surface ofsaid refractor panel.
 4. A luminaire as defined in claim 3, said flutesbeing of substantially constant refractive power along their lengths. 5.A luminaire as defined in claim 1, a ballast housing arranged above andconnected to said optical assembly for supporting the same, and anaccessory reflector mounted at the bottom of said ballast housing abovesaid upper reflector portion for reflecting light rays from said lampdownwardly through said refractor.
 6. A luminaire as defined in claim 1,said reflector portions being formed with flutes for horizontallyspreading lighT rays from said lamp.
 7. A luminaire as defined in claim1, the height of said reflector being about twice the height of saidrefractor.
 8. A luminaire as defined in claim 7, the overall diameter ofsaid optical assembly being at least twice its height.